Interesting. I have never looked at waterfall graphs before. So most of the LFE is in the 30-60Hz range with stuff pushing down to 18-20Hz and very occasionally lower.
Which is why being able to play below 20hz is not that critical and not really missed. In my A/B testing I could tell which subs went lower but I also never felt I was really missing anything with the higher tuned subs.
The PB12-NSD I have here plays down in to the teens just like the PB13, but the driver size, box size, amp all play a part in how each sub sounds. The PB13 has a more airy, encompassing sound to it compared to the PB12. The EP600 has an even more encompassing sound to it than the PB13. I am quite certain the PB13 reaches lower than the EP600 but it isn't missed when listening to the EP600. These are the types of things graphs are unable to show.
